QUIZ 5 ANSWER KEY
Market Structure
Version A
I. Multiple Choice
(1)f. (2)e. (3)a. (4)c. (5)b. (6)b. (7)b. (8)b. (9)b. (10)b.
II. Problems
(1) [Measuring industry concentration: 18 pts]
- Firm 1.
- 80.
- 90.
- Industry B.
- 3000.
- 2100.
- Industry A.
- 0.15 .
- 0.105 .
(2) [Entry barriers and contestable markets: 26 pts]
- $2.
- 6 million.
- 2/3 = 0.667.
- $3.
- $4.
- loss.
- $3 million.
- 9 million.
- $2.
- profit.
- $27 million.
- $2.
- 0, since P = MC.
(3) [Dominant-firm price leadership: 30 pts]
- $4.
- $10.
- 1 million.
- 10 million.
- Residual demand is a straight line, has vertical intercept at P=$10, and touches market demand curve at $4, according to answers to parts (a) and (b) above. Slope is therefore = 1 / 2 million.
- Residual demand is a straight line, with same intercept and twice the slope as residual marginal revenue. Slope is therefore = 1 / 1 million.
- 8 million.
- $6.
- 2 million.
- 2/3 = 0.667 .
II. Critical Thinking
A credible threat is one that a firm has an incentive actually to carry out. This particular threat by Firm A is not credible, because if Firm B were to enter the market, Firm A would have no incentive to lower below its average cost, because in doing so, Firm A would make losses. Since Firm B has the same costs as Firm A, there is no reason to believe that a price war would induce Firm B to exit the market any sooner than Firm A.
Version B
I. Multiple Choice
(1)e. (2)f. (3)c. (4)a. (5)a. (6)a. (7)d. (8)c. (9)a. (10)a.
II. Problems
(1) [Measuring industry concentration: 18 pts]
- Firm 7.
- 70.
- 70.
- Equally concentrated.
- 1600.
- 2200.
- Industry B.
- 0.08 .
- 0.11 .
(2) [Entry barriers and contestable markets: 26 pts]
- $3.
- 7 million.
- 4/7 = 0.571.
- $4.
- $7.
- loss.
- $9 million.
- 8 million.
- $3.
- profit.
- $24 million.
- $3.
- 0, since P = MC.
(3) [Dominant-firm price leadership: 30 pts]
- $2.
- $9.
- 3 million.
- 8 million.
- Residual demand is a straight line, has vertical intercept at P=$9, and touches market demand curve at $2, according to answers to parts (a) and (b) above. Slope is therefore = 1 / 2 million.
- Residual demand is a straight line, with same intercept and twice the slope as residual marginal revenue. Slope is therefore = 1 / 1 million.
- 6 million.
- $6.
- 4 million.
- 0.5 .
II. Critical Thinking
Same as Version A.
[end of answer key]